<jats:title>Abstract</jats:title><jats:p>A method for the determination of the pyrrolizidine alkaloids from <jats:italic>Senecio jacobaea</jats:italic> (Compositae) by <jats:sup>1</jats:sup>H and <jats:sup>13</jats:sup>C NMR is presented. <jats:sup>1</jats:sup>H NMR is a reliable method for the determination of the total alkaloid level. <jats:sup>13</jats:sup>C NMR appears to be a suitable method for the determination of the individual alkaloids. The same techniques can also be applied to other plants containing pyrrolizidine alkaloids.